cleaning roor and pyrex 8 arm diffuser

hey guys, I have tried many things to clean these things. I have heard the 420 cleaning is over priced, so i tried the rubbing alcohol, salt and hot water and it did not clean it as well as i anticipated. Is there any other way to clean it the best? I heard someone mention boiling water, any feelings on that?:DVia (only registered users can se the link, login or register)